Approximately 65% of service members seriously injured in Iraq and Afghanistan sustain injuries to their extremities. Many of these individuals experience muscle tissue loss and/or nerve injury, resulting in the loss of limb function or substantial reduction thereof. Injuries to the lower leg can be particularly devastating, due to the critical importance of the ankle in providing support for body position and in propelling the body forward economically during common functions, such as level-ground walking and the ascent and descent of stairs and slopes.
Increasingly, robotic technology is employed in the treatment of individuals suffering from physical disability, either for the advancement of therapy tools or as permanent assistive devices. An important class of robotic devices provides therapy to the arms of stroke patients. Additionally, lower-extremity robotic devices have been developed for the enhancement of locomotor function. Although decades of research has been conducted in the area of active permanent assistive devices for the treatment of lower-extremity pathology, many of these devices are not designed to produce a biomimetic response, generally described in terms of joint torque, joint angle, and other related parameters as observed in a human not having substantial muscle tissue injury and not using any device to assist in ambulation. Therefore, these robotic devices may cause discomfort to the wearer. The commercially available ankle-foot orthotic devices are generally passive, non-adaptive devices.
Some powered prosthetic and orthotic devices have been described in co-pending U.S. patent application Ser. No. 12/157,727 “Powered Ankle-Foot Prosthesis” filed on Jun. 12, 2008 (Publication No. US2011/0257764 A1); co-pending U.S. patent application Ser. No. 12/552,013 “Hybrid Terrain-Adaptive Lower-Extremity Systems” filed on Sep. 1, 2009 (Publication No. US2010/0179668 A1); co-pending U.S. patent application Ser. No. 13/079,564 “Controlling Power in a Prosthesis or Orthosis Based on Predicted Walking Speed or Surrogate for Same” filed on Apr. 4, 2011; co-pending U.S. patent application Ser. No. 13/079,571 “Controlling Torque in a Prosthesis or Orthosis Based on a Deflection of Series Elastic Element” filed on Apr. 4, 2011; and co-pending U.S. patent application Ser. No. 13/347,443 “Powered Joint Orthosis” filed on Jan. 10, 2012. These powered devices are adopted to provide at least a biomimetic response and can eliminate or mitigate slapping of the foot after heel strike (foot slap) and dragging of the toe during swing (toe drag). In general, a biomimetic response refers to a range of responses from humans and can vary according to the wearer of the powered device and the nature and environment of the wearer's activity. As such, even the powered devices described above need to be tailored or calibrated to the wearer so as to reliably provide a biomimetic response. Therefore, there is a need for systems and methods of controlling permanent assistive devices for the treatment of lower-extremity pathology to achieve optimal wearer comfort and satisfaction.